Various systems and methods for drilling boreholes are known in the art and have been used for decades in a wide variety of applications, from oil and gas, to mining, to quarrying operations, just to name a few. In mining and quarrying operations, such boreholes are typically filled with an explosive that, when detonated, ruptures or fragments the surrounding rock. Thereafter, the fragmented material can be removed and processed in a manner consistent with the particular operation. When used for this purpose, then, such boreholes are commonly referred to as “blastholes,” although the terms may be used interchangeably.
A number of factors influence the effectiveness of the blast, including the nature of the geologic structure (i.e., rock), the size and spacing of the blastholes, the burden (i.e., distance to the free face of the geologic structure), the type, amount, and placement of the explosive, as well as the order in which the blastholes are detonated. Generally speaking, the size, spacing, and depth of the blastholes represent the primary means of controlling the degree of rupture or fragmentation of the geologic structure, and considerable effort goes into developing a blasthole specification that will produce the desired result. Because the actual results of the blasting operation are highly correlated with the degree to which the actual blastholes conform to the desired blasthole specification, it is important to ensure that the actual blastholes conform as closely as possible to the desired specification.
Unfortunately, however, it has proven difficult to form or drill blastholes that truly conform to the desired specification. First, a typical blasting operation involves the formation several tens, if not hundreds, of blastholes, each of which must be drilled in proper location (i.e., to form the desired blasthole pattern) and to the proper depth. Thus, even where it is possible to achieve a relatively high hole compliance rate (i.e., the percentage of blastholes that comply with the desired specification), the large number of blastholes involved in a typical operation means that a significant number of blastholes nevertheless may fail to comply with the specification. In addition, even where blastholes are drilled that do comply with the desired specification, a number of post-drilling events, primarily cave-ins, can make a blasthole non-compliant. Indeed, such post-drilling events can be major contributors to blasthole non-compliance.
Still further, because of the large number of blastholes that are typically required for a single blasting operation, methods are constantly being sought that will allow the blastholes to be formed or drilled as rapidly as possible. As with most endeavors, however, there is an inverse relationship between speed and quality, and systems that work to increase speed at which a series of blastholes can be drilled usually come at the expense of hole quality. Consequently, there is a need for methods and systems for forming blastholes that will ensure consistent blasthole quality while minimizing the adverse affects on the speed of blasthole formation.